id:A124316 - OEIS Search Results

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a(n) = Sum_{ d divides n } sigma_1(lcm(d,n/d)), where sigma is the sum of divisors function.

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1, 2, 2, 5, 2, 4, 2, 8, 6, 4, 2, 10, 2, 4, 4, 15, 2, 12, 2, 10, 4, 4, 2, 16, 8, 4, 10, 10, 2, 8, 2, 22, 4, 4, 4, 30, 2, 4, 4, 16, 2, 8, 2, 10, 12, 4, 2, 30, 10, 16, 4, 10, 2, 20, 4, 16, 4, 4, 2, 20, 2, 4, 12, 37, 4, 8, 2, 10, 4, 8, 2, 48, 2, 4, 16, 10, 4, 8, 2, 30, 23, 4, 2, 20, 4, 4, 4, 16, 2, 24 (list; graph; listen)

	OFFSET	`1,2`
	MATHEMATICA	`Table[Plus @@ Map[DivisorSigma[1, GCD[ #, n/# ]] &, Divisors@n], {n, 90}]`
	CROSSREFS	`Cf. A001616, A061884, A124315.` `Sequence in context: A021448 A108053 A133501 this_sequence A061034 A111861 A004543` `Adjacent sequences: A124313 A124314 A124315 this_sequence A124317 A124318 A124319`
	KEYWORD	`nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 30 2006`

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Last modified December 15 00:47 EST 2009. Contains 170825 sequences.

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